不同土质中模型支盘桩在重复荷载作用下的试验研究

EXPERIMENTAL RESEARCH ON MODEL PILE WITH PLATES AND BRANCHES UNDER REPEATED LOADING IN DIFFERENT SOILS

为研究支盘桩在不同土质中重复加载下的工程性状,分别对一个双盘模型支盘桩在粉土和粉质黏土中进行5次重复加载–卸载试验,所加最大荷载小于该模型桩的极限承载力。根据试验结果,分析在两种不同土层中支盘桩的承载力和变形特性,研究两者荷载传递的特点和异同、桩身不同位置压力变化的特点和异同,特别是对桩周土体对桩侧表面产生的摩擦力在不同条件下会出现复杂变化的原因进行分析。还分析离盘不同距离的土体在重复加载过程中的压力变化情况和原因。研究结果表明,不同土质条件对支盘桩的承载力和变形有很大不同,粉土中的工程性状要优于粉质黏土,而不同土层中支盘桩和桩周土体的相互作用机制也是明显不同并且十分复杂。因此要充分认识支盘桩在重复荷载作用下的工程性状和荷载传递机制还要进行大量研究。

The model pile with two plates is loaded and unloaded for 5 times in silt and silty clay to study the engineering behavior of pile with plates and branches under repeated loading in different soils.The biggest load is less than the limit bearing capacity.According to the test resultt,he bearing capacity and deformation characteristic of the pile in different soils are analyzed;and the load transfer behavior and the pressure change of the different places on pile under the two situation are studied,especially the reason why the surface friction between soil and pile under different conditions will appear complex change.For example,in silt with lower water content,the frictional resistance from the soil between plates and pile shows positive one on the upper section,while minus on the lower section.However,in silty clay with higher water content,it is just opposite,minus on the upper section and positive on the lower section.This phenomenon can be explained by the formation,development and failure mechanisms of soil arch under different soil conditions.In addition,the situation and reason of the soil pressure change at different distances away from the plate are analyzed.It is found that the bearing capacity and deformation of the pile with plates and branches are obviously different for different soils,silt is better than silty clay;the mutual effect of pile and soil around it is obviously different and complex.So a lot of studies should be done to understand the project behavior and load transfer behavior of the pile with plates and branches under repeated loading.